Weird indeed, and needs to be investigated. Have you done a few resets and power-cycles just to be sure ?
Any chance you are using revision-control with your source-code ? Sometimes there are other changes you made, but forgot. I know it sounds stupid, but I've done it many times myself and the evidence was right there, thanks to git (or whatever source-control you use). Years ago, I have also seen bugs in CAD tools. Anyone here remember CUPL ? It was a tool used for generating PLA code from logic equations. Sometimes as you got close to filling-up the device, the tool would report you ran out of logic elements. But, if you were lucky, simply re-arranging lines of code got it to fit-in. It seems unlikely that Teensy would have this problem, but you never know. On Sunday, June 23, 2024 at 10:19:05 AM UTC-7 Max DN wrote: > So, it seems it is now working as expected, although I'm not counting my > chickens yet. In the SPI routine from the Teensy to the DAC, I changed the > gain for the DAC from two to one, loaded the code, edited the code back to > a gain of two in the DAC, loaded it again and voila'. Odd! > > It's working as expected. Although I don't understand why! > > Il giorno domenica 23 giugno 2024 alle 02:46:09 UTC+1 gregebert ha scritto: > >> So another possibility is that one of the amplifiers is clipping, usually >> because the input signals are trying to drive the output beyond the supply >> rails. BTW, most op-amps are not rail-to-rail, but they can get pretty >> close. It will show up quickly on a scope. >> >> On Saturday, June 22, 2024 at 3:35:15 PM UTC-7 Dekatron42 wrote: >> >>> So what happens if you put this Teensy in the other working board, does >>> the error follow the Teensy? >>> >>> If so, have you tried to reprogram the Teensy or even erase it to set >>> it to its original setup condition? >>> >>> /Martin >>> >>> On Saturday 22 June 2024 at 22:48:49 UTC+2 Max DN wrote: >>> >>>> @Martin, if I try to bypass the DAC using POTs for NEG5 and POS5 it all >>>> seems fine (the dot goes across the whole X axis and Y axis). >>>> @gregebert, no Z-axis. >>>> >>>> I am probing X and Y just out of the DAC and not connected to anything >>>> else. I can see the image on the oscilloscope as a full round circle, but >>>> as I try to center it to what would be the center of the CRT then thr >>>> circle flatlines. >>>> >>>> It feels as though past a certain point on the vertical axis, the dots >>>> are just collapsing into the same line and cannot go past (on one end of >>>> the Y vertical axis, X axis is fine). >>>> >>>> Very odd as I have already used same code and same pcb for another >>>> scope clock. After 10 hours on it today, I'm going to let go until I have >>>> any other ideas. I have tried replacing the processor, the DAC (3 times), >>>> checked all resistors and bypass caps and triple checked all soldering >>>> points. Maybe it's time to bin this pcb, but I do like a challenge! >>>> >>>> >>>> Il giorno sabato 22 giugno 2024 alle 16:38:19 UTC+1 gregebert ha >>>> scritto: >>>> >>>>> Is there a Z-axis ??? That would be my first suspect; if the trace is >>>>> still visible, then the appropriate grid needs to be driven a bit more >>>>> negative. >>>>> >>>>> If the CRT uses rapid movement for dark (technically dim) regions, and >>>>> slower movement for bright regions, then my best guess is some kind of >>>>> software tweak would be needed to get the beam to move faster, or off the >>>>> phosphor-coated area (or both). >>>>> >>>>> On Saturday, June 22, 2024 at 3:49:04 AM UTC-7 Dekatron42 wrote: >>>>> >>>>>> Can you remove the processor and feed the amplifiers directly from a >>>>>> potentiometer connected to NEG5 and POS5 and see how the dot moves on >>>>>> the >>>>>> screen? You need one potentiometer for X & Y so that the dot will appear >>>>>> on >>>>>> screen. This way you will test out the amplifier chains without the DAC >>>>>> involved. >>>>>> >>>>>> /Martin >>>>>> >>>>>> On Saturday 22 June 2024 at 12:10:54 UTC+2 Max DN wrote: >>>>>> >>>>>>> Martin, that's what I am thinking... however I don't think it's the >>>>>>> amplifier chain as I get the same issue if I just display X and Y >>>>>>> signals >>>>>>> straight out of the DAC on the oscilloscope. That brings it down to a >>>>>>> few >>>>>>> components only: 2 potentiometers for centerting X and Y, their two >>>>>>> bypass >>>>>>> capacitors, the DAC and its 1 bypass capacitors, the +3.3V Linear >>>>>>> regulator, the +5V supply to the DAC. I'm going to try and replace >>>>>>> everything once more by one by one... Not the smartest way of doing it >>>>>>> but >>>>>>> let's see what it brings... >>>>>>> >>>>>>> Il giorno sabato 22 giugno 2024 alle 11:01:12 UTC+1 Dekatron42 ha >>>>>>> scritto: >>>>>>> >>>>>>>> Could it be the that any of the power lines sags as the signal >>>>>>>> tries to increase to the right (in the picture right where the line >>>>>>>> is) or >>>>>>>> that any of the resistors in the amplifier chain has an incorrect >>>>>>>> value? >>>>>>>> >>>>>>>> /Martin >>>>>>>> >>>>>>>> On Saturday 22 June 2024 at 11:32:21 UTC+2 Max DN wrote: >>>>>>>> >>>>>>>>> Tried to replace a few more parts, including potentiometers for >>>>>>>>> Focus and Intensity, made no difference. So, back to basics: using an >>>>>>>>> oscilloscope I see that the X and Y signals straight out of the DAC >>>>>>>>> look >>>>>>>>> exactly the same as in the picture I had attached. Maybe a faulty >>>>>>>>> DAC? >>>>>>>>> Tried to replace the DAC twice with new ones and made no difference. >>>>>>>>> Looks >>>>>>>>> like I'm hitting some sort of physical limits... More debugging to >>>>>>>>> do... >>>>>>>>> >>>>>>>>> Il giorno venerdì 21 giugno 2024 alle 18:31:51 UTC+1 Max DN ha >>>>>>>>> scritto: >>>>>>>>> >>>>>>>>>> Hello, >>>>>>>>>> >>>>>>>>>> I'm building a scope clock, same board as another one I built >>>>>>>>>> before with no issues (after some help I got on this group, thank >>>>>>>>>> you!) and >>>>>>>>>> I'm getting a flat line on the display. >>>>>>>>>> >>>>>>>>>> I have tried replacing the CRT, the DAC, the Op Amps and the >>>>>>>>>> MPSW42 deflection amplifiers but made no difference. CRT is 3RP1A. >>>>>>>>>> Code and >>>>>>>>>> circuitry have been fully tested on another working board. >>>>>>>>>> >>>>>>>>>> I do recall having a similar issue before with a DH3/91 CRT and I >>>>>>>>>> seem to recall that I just needed to adjust the pot for Astigmatism >>>>>>>>>> that >>>>>>>>>> controls the voltage on A2. Schematics as in here: >>>>>>>>>> http://www.cathodecorner.com/sctv/sctv-schem-2.png >>>>>>>>>> >>>>>>>>>> I'm a bit at a loss here, although I'm sure it's something simple >>>>>>>>>> that I'm missing. >>>>>>>>>> >>>>>>>>>> Pic attached. >>>>>>>>>> >>>>>>>>>> Any suggestions welcome, >>>>>>>>>> >>>>>>>>>> Max >>>>>>>>>> >>>>>>>>> -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. 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